You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
33 lines
672 B
33 lines
672 B
8 years ago
|
#include <assert.h>
|
||
|
|
#include <sys/mman.h>
|
||
|
|
|
||
|
|
#include "hook.h"
|
||
|
|
|
||
|
|
#pragma pack(push, 1)
|
||
|
|
struct hook_jmp_rel32 {
|
||
|
|
uint8_t op;
|
||
|
|
int32_t offset;
|
||
|
|
};
|
||
|
|
#pragma pack(pop)
|
||
|
|
|
||
|
|
static void hook_assemble_jump(void *at, void *to)
|
||
|
|
{
|
||
|
|
hook_jmp_rel32 *jmp = (hook_jmp_rel32 *)at;
|
||
|
|
|
||
|
|
jmp->op = 0xE9;
|
||
|
|
jmp->offset = (intptr_t)to - ((intptr_t)at + sizeof(*jmp));
|
||
|
|
}
|
||
|
|
|
||
|
|
static int hook_unprotect(void *address, size_t size)
|
||
|
|
{
|
||
|
|
// Align to bottom of page
|
||
|
|
address = (void *)((uintptr_t)address & ~(4096 - 1));
|
||
|
|
return mprotect(address, size, PROT_READ | PROT_WRITE | PROT_EXEC);
|
||
|
|
}
|
||
|
|
|
||
|
|
void hook(void *at, void *to)
|
||
|
|
{
|
||
|
|
assert(hook_unprotect(at, sizeof(hook_jmp_rel32)) == 0);
|
||
|
|
hook_assemble_jump(at, to);
|
||
|
|
}
|